Concrete gun



Oct. 14', 1930.

w. F. WEBB CONCRETE GUN Filed Sept. 21 1926 INVENTOR. W/m 7% A M ATTORNEY Patented Get. 14, 1930 UNITED STATES PATENT OFFICE WADE WEBB, OF OAKLAND, CALIFORNIA corronnrn GUN Application filed September 21, 1926. Serial No.1 136,848;

My invention relates to a device for forcibly inipelling by means of compressed air or some other suitable fluid substance, concrete or the like in a plastic state, through a conduit and into suitable forms, and especially relates to the pneumatic discharge of concrete at a comparatively low velocity and with a minimum air consumption due to the low air pressure used.

In other types of devices used for this purpose, tvvo or more jets of air are used for forcing concrete or the like from the container and conveying same through the conduit. It is recogmzed that with the use of two or more air ets an excess of air 1s consumed due to the fact thatthe amount of f concrete in front of the effective or conveylug et 1s variable;.at times little, or no concrete is in front of the jet and air is wasted; and at other times too much concrete-is in front of the jet and a plug occurs in the reducer of the container. It is further recognized that due to the nature of the material, concrete cannot be forced from a large container to a comparatively small conduit by the same method as would be used for water, that is by pressure applied in the rear of the mass; if this method is resorted to the concrete will plug in the reducer, and the more pressureapplied the harder the plug willbecome and the container must be opened and the plug broken up by hand. To avoid I clogging and to continuously and successfully feed concrete from the container to the conduit the amount of concrete in front of 1 the delivery jet should never exceed the ca- .-use of compressed air; and further, to supply a means for breaking a plug, without open- 1 ing the container, should same occur from improper manipulation or otherwise.

Other and ancillary objects and purposes will be outlined in the specification accompanying and forming part of this application, and further purposes will be suggested by the particular uses my improved device encounters.

In the drawings:

Figure 1 is a longitudinal median section of the gun of my invention, and Fig. 2 is an enlarged plan of the air-nozzle in detail.

A substantially cylindrical container 2 ta pers to an ejection throat 4- at its lower portion, is provided with an opening at 6 for the concrete supply 7, a fluid-tight closure 8 for said opening, and a source 10 of compressed air leading to an air nozzle 11 for ejecting the concrete.

The ejection throat t may lead directly to a concrete delivery spout, or may be connected to a pipe line for conveying the conh crete. It is preferably tapered as shown to provide a reducer facilitating entrance of the concrete into the ejection line.

The opening at 6 is provided witha neck 12 into which the concrete mixture may be dumped tofill the gun. The air pressure in the gun, and the sticky and abrasive charactor of the concrete require unusual means for closing this opening (5, and for this purpose I provide a Wedge-shaped slit or guide- Y way in the neck 12, transversely ofthe opening 6:, and a complementary wedge-shaped cover 8 forthe slit. The amount of taper of the Wedge is clearly shown by the sectional view of the cover in Fig. 1, and the cover extends across the opening 6 to completely close it when in the left-hand position shown in the figure. .The taper of the cover 8 insures a tight seat and causes the abrasive in the concrete to merely grind the cover to a smooth seat rather than to damage it.

Means are provided for opening and closing the cover. A compressed air cylinder 16 has its piston 18 connected by a rod 20 directly to the cover 8; and pipes 22 and 2 L .jconcrete. in the gun. proportion for maximum el'hciency 1s varilead from each end of the cylinder to manually controllable two-way valves 26 and In one position, the valves communicate with the air line 10, and in the other position they lead to the atmosphere. F or simplicity of description, the fact that the two halves 26 and 28 may bereplaced by a single three way valve, is ignored.

Concrete is a. thick plastic mass, and in order to facilitate its flow it is. necessary to feed the concrete to the conduit in an amount not. injexcess of the capacity of the conduit.

This prevents clogging and waste of air. The nozzle 11 therefore is positioned in the bottom of the container. There is, obviously, a'proper proportion of air to concrete for most eflicient ejection, and this ratio depends upon such factors as the air pressure, upon the length and constriction of the ejection line, and thedensity and quantity of In other Words the an opening at 3 6 in the container. A packing gland 3 8 prevents leakage of concrete through the opening, and tends to prevent passage of airtherethrough. A cylinder 40 has its axis parallel to the pipe 34'and is bolted or otherwise attached at its open end,

to the container 2 in enveloping eccentric relation to the opening at 36. A piston 42 in the cylinder, is fixedlyv connected by an offset rod 44 to the pipe 34. This oilset relation restrains the assembly from rotation. The rod 44 is merely a SOllCl connecting bar Air and has no air passage formed in it. supply to the cyhn ler and nozzle will nextbe explained.

A manually controlled two-way valve 45 connects the outer end of the cyhnder 40 selectively to the air line 10 or to'atmospheric exhaust. The inner end of the cylinder 40 may be connected to the air line 10 by a manually controllable valve 46 having no atmospheric exhaust. Thus the inner (righthand in Fig. 1) end of the cylinder cannot be directly exhausted and so its pressure cannot drop belowthe pressure in the: container 2. An adjustable regulating valve 48 of'the safety valve type, isheld closed by a spring 50 and permits escape of air when the pressure diiference exceeds a few pounds per square inch, fron'1 thelinner end of the cylinder 40 to the nozzle pipe 34. Thus t ie valve 46 controls the injection of air into the container 2,while the valve 48 regulates the pressure of the air therein. The nozzle 11 duit.

is moved away from the threat 4 by pressure of airagainstthe piston 42, this air being admitted through valve 46 While valve 45 is opened to the atmosphere, the latter relation of the valves being indicatedin Figure 1. The movement of the piston 42 toward the throat 4 is produced by air admitted by valve 45 to the cylinder 40.

A rod 52 extends from one end of the piston 42 out through a packing gland 54 in the outer cylinder head 56, and has index marks cooperating with a pointer 58', to in dicate the position of the nozzle within the gun. The nozzle '11 when Withdrawn from the throat of the container 2 at the manually controlled and determined rate of speed, will supply a steady flow of concrete, not in excess of the capacity of the conduit, to the conduit, thus,- the maximum amount of concrete may be supplied to the conduit with a minimumconsumption of air and without clogging.

The action. of the air on the concrete is enhanced by the shape of the nozzle orifice. As shown in the figures, the end of the pipe 34, is tapered to a slot 60 and additional apertures 62, 64 and 66, in the top and sides throw a, radiating blast of air into the concrete mass. surfaces lie outsideof the confining lines of At no point shall the nozzle.

the pipe 34, so as not to incur friction in 're-' cipro'cating the nozzle 11. The cross-sectional area of'slot 60 and apertures 62, 64

and 66 is preferably about equal to that of the pipe 34.

The slot 60 lies closeto'the bottom ofthe container and the air'coming from'this slot will dislodge all concrete from the bottom of the container and force said concrete into and through the conduit. v blasts from apertures 62, 64 and 66 will dislodge all concrete above t-henozzle .11 and cause said concrete to drop to the bottom'of the container where. it will be subject to the blast issuing from the slot- 60. The air coming from' apertures 62, 64 and 66 Will also The radiating assist in expelling the concrete from the con- Should a jam occur :inthe throat-of the container, the 'air supply will be shut 0d at valve 46 and the air pressure in the container reduced to atmosphere by means of the manually operable relief valve 68. hen this has been done the nozzle 11 will .be forced into the throat of the container by air pressure applied on the piston 42 through the valve 45, and air will then be supplied to the nozzle 11 with the resultant'breaking of the jam. As the nozzle is retracted the rezle 11. The position ofthis nozzle is next adjusted by manipulation of'the valve 45;

mainder of the concrete will be discharged. Y

being moved away from the throat by opening the valve 45 toa-tmospheric exhaust, and being moved toward the throat by opening the valve 45 in the opposite direction to connect with the pressure line 10. The rate of concrete ejection is regulated by means of the valve 46, and the nozzle 11 is maintained I I in the most effective position by control of the valve 45.

here desired, the cylinder 40, instead of extending beyond the gun as illustrated, may be arranged alongside the gun. The present arrangement is preferable when the available tunnel space permits of its use. The gun may be mounted on any desirable means.

Parts not specifically referred to, are ordinary structural parts and consequently are not described. The WOI'Cl concrete is to be understood to refer to concrete, or to cement,

mortar or other like materials, and the term connected to said pipe, a cylinder surrounding said pistommeans for selectively supplying compressed air to either side of said piston, means permitting passage of compressed air from one side of said piston into said pipe,

and means for preventing passage of concrete into said cylinder.

2. In a pneumatic concrete gun forforclbly ejecting concrete, a closed container having a discharge opening for the concrete, a

. source of compressed air for impelling the concrete, a tapered nozzle adapted to discharge air along the lower wall of the container and having apertures in the upper and outer portions thereof for discharging air upward and sideways, and means for moving said nozzle along the'low'er wall of the container.

3. In apneumatic concrete gun for forcibly ejecting concrete, a closed container hav ing a discharge opening for the concrete, a source of compressed air for impelhng the concrete, a tapered nozzle adapted to discharge air along the lower wall of the con tainer and having apertures in the upper and outer portions thereof for discharging air upward and sideways, means for restraining said nozzle against angular displacement,

and means for moving said nozzle along the lower wall of the container.

v 4;. A pneumatic concrete gun comprising a container having a discharge opening from its lower portion and an aperture therethrough opposite said opening, a blower pipe slidably engaged in said aperture, a nozzle at the end of said pipe, a piston connected to said pipe, a cylinder surrounding said piston, means for selectively supplying compressed air to either side of said piston, and means permitting passage of compressed air from one side of said piston into said pipe.

In testimony whereof, I affix my signature.

WADE F. WEBB. 

